Explanation: Near the end of the Hundred Years' War, the English were pretty decisively winning. Things looked dire for France. But a teenaged peasant girl known as Joan of Arc rose out of the chaos. As a child, she had been deeply interested in military matters, but forbidden by the norms of her time and class from taking up arms. In her late teens, however, she began to hear voices, and became convinced that she was chosen by God to cast out the English from France.
With intense charisma and religious fervor, she managed to convinced a number of soldiers and knights to support her cause with nothing more to her name than a fire in her eyes and the ability to evoke hope in the hearts of the French. After meeting the French monarch with her companions, she was given armor, a sword, and a banner, and with these led the French forces to several victories - though primarily as a standard-bearer and commander, rather than swinging her sword.
Now, while her claim was divine inspiration, and she may have believed that, she also showed a keen intellect and an awareness of rational military operations, including the then-cutting-edge black powder.
Reduced support from the French crown as France's war situation improved eventually led to her being captured by English-allied forces, where she was tried for a variety of religious crimes. She was eventually burned at the stake for the crime of heresy, as evidenced by [checks notes] wearing men's clothing.
France would go on to foil the English invasion and eventually win the Hundred Years' War after another two decades of fighting.